Sleep is one of nature’s ways to help the body stay healthy, and in babies it is even more important, as their immune systems have not completely developed. Melatonin is a hormone regulating sleep and wake cycles, and the varying levels in the body have been shown to positively or negatively affect the immune system. When your baby is sick, you may notice that she wants to sleep more. Let her sleep as long as she needs. In a few instances, however, you might need to be concerned and consult her pediatrician.

How Much Sleep

When your baby is healthy and under 6 months old, she will sleep between 16 and 20 hours every day, divided between day and night, according to KidsHealth.org. Between 6 and 12 months, your baby will sleep about 9 to 11 hours at night and about 3 hours during the day. However, each child is different, and individual children may need more or less sleep. Disturbed sleep or a lack of sleep has been linked to weakened immune systems and increased susceptibility to colds, according to a 2009 study published in the “Archives of Internal Medicine.”

Sickness

When your baby is sick, however, his body needs all the rest it can get. Sleep coach Linda Boston recommends that you try to keep your baby on his usual sleep routine while he is sick. However, if he naps more, let him sleep. If his symptoms make it harder to fall asleep, try tricks like a ride in the stroller if he can’t fall asleep on his own. You might need to sleep in his room or put a chair by his bed if he experiences heightened separation anxiety while sick. A humidifier and using a bulb syringe to clean his nasal passages before bed may also help.

When to Be Concerned

If your baby is having trouble getting to sleep and staying asleep for extended periods of time, talk to your baby’s doctor. Many illnesses come with sleeplessness, and your pediatrician may be able to help you find ways to help your baby sleep and heal. If your baby refuses to wake to nurse or take a bottle, consult your pediatrician as well, as your baby needs nutrition and liquids to get healthy again. Very young babies that still need to be woken up to reach their target weight miss vital nutrition and liquids if they sleep through too many meals.

Lethargy

Lethargy is another situation in which your baby needs to see the doctor. She may be lethargic if you have a difficult time waking her for feedings on a regular basis, if she is sleepy or sluggish while she is awake, and if she does not pay attention to sound or visual stimulation. Lethargy often develops over a period of time, and it can be difficult to identify. Lethargy can also be a sign of dehydration in newborns, highlighting the need to encourage your baby to nurse or take a bottle.